Since the end of the Little Ice Age (LIA), Svalbard glaciers have undergone a net retreat in response to changing meteorological conditions. Located between 76{\textdegree}N and 80{\textdegree}N, western Spitsbergen has seen a climatic transition from a glacial to a paraglacial system. On the northern shore of the Br{\o}gger Peninsula (northwest Spitsbergen), the average temperature increased by 3\ {\textdegree}C between 1965 and 2015, and cold-based valley glaciers have retreated more than 1\ km from their LIA limits. This rapid deglaciation has exposed large areas of glacigenic sediments being easily reworked by runoff. This has led to the formation of extensive glacier-river delta systems and coastal progradation. Post-LIA coastal progradation and formation of new landforms in Kongsfjorden have been controlled predominantly by substantial availability of glacial sediment. A combination of aerial photographic and field data has been employed to estimate the post-LIA evolution of coastal sandur deltas and their submarine parts (named here {\textquotedblleft}prodeltas{\textquotedblright}). The data set reveals that delta shoreline advance could have reached around 5\ m/year. between 1966 and 1990 for the most energetic delta of Austre Lovenbreen, and around 4\ m/year between 2011 and 2014 for the most energetic delta of Midtre Lovenbreen. The prodeltas registered a net growth from 2009 to 2012: the biggest, located in the prolongation of deltas of Austre Lovenbreen, measured 1033\ m in length in 2009 and 1180\ m in length in 2012. This substantial amount of sediment supplied in the fjord has an impact on the fjord ecology, especially on the benthic ecosystem.